A comparison of hepatotoxicity induced by different lengths of tungsten trioxide nanorods and the protective effects of melatonin in BALB/c mice.

Tungsten trioxide nanoparticles (WO3 NPs) have shown increasing promise in biological and biomedical fields in recent years. However, their possible hazards, especially the adverse effects related to their sizes on human health and environment, are still yet poorly understood. In this study, we compared the hepatotoxicity in mice induced by WO3 nanorods of two different lengths (125-200 nm and 0.8-2 μm) via intraperitoneal injection, and explored the protective role of melatonin, an antioxidant, against the hepatotoxicity. The results showed that 10 mg/kg/day of shorter WO3 nanorods could cause obvious hepatic function impairment, histopathological lesions, and significant enhancement in levels of oxidative stress and inflammation in mouse liver. However, similar effects were found only in the 20 mg/kg/day longer WO3 nanorods-treated mice, and these adverse effects were attenuated by pretreatment with melatonin. These findings indicate that WO3 nanorods can exert hepatotoxicity in mice in a dose- and length-dependent manner, and that shorter WO3 nanorods cause more severe hepatotoxicity than their longer counterparts. Melatonin could serve as an effective protective agent against the longer WO3 nanorods-induced hepatotoxicity by decreasing the oxidative stress level. This study is important for determining the environmental and human health risks of exposure to WO3 NPs and their size-dependent toxicity, and provides an appealing strategy to avoid the adverse effects. WO3 nanorods with different lengths can exert hepatotoxicity in mice, in a dose- and length-dependent manner. Short WO3 nanorods causes more severe hepatic injury than long ones. Melatonin exhibits an effectively protective effects against WO3 nanorods-induced hepatic injury through reducing the oxidative stress level.